如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
当前回答
在Groovy中
inputStream.getText()
其他回答
我已经创建了这段代码,并且它有效。没有所需的外部插件。
有一个字符串到流和流到字符串的转换器:
import java.io.ByteArrayInputStream;
import java.io.InputStream;
public class STRINGTOSTREAM {
public static void main(String[] args)
{
String text = "Hello Bhola..!\nMy Name Is Kishan ";
InputStream strm = new ByteArrayInputStream(text.getBytes()); // Convert String to Stream
String data = streamTostring(strm);
System.out.println(data);
}
static String streamTostring(InputStream stream)
{
String data = "";
try
{
StringBuilder stringbuld = new StringBuilder();
int i;
while ((i=stream.read())!=-1)
{
stringbuld.append((char)i);
}
data = stringbuld.toString();
}
catch(Exception e)
{
data = "No data Streamed.";
}
return data;
}
这个很好,因为:
它可以安全地处理Charset。您可以控制读取缓冲区的大小。您可以设置生成器的长度,而不必是精确的值。不受库依赖关系的影响。适用于Java 7或更高版本。
怎么做?
public static String convertStreamToString(InputStream is) throws IOException {
StringBuilder sb = new StringBuilder(2048); // Define a size if you have an idea of it.
char[] read = new char[128]; // Your buffer size.
try (InputStreamReader ir = new InputStreamReader(is, StandardCharsets.UTF_8)) {
for (int i; -1 != (i = ir.read(read)); sb.append(read, 0, i));
}
return sb.toString();
}
对于JDK 9
public static String inputStreamString(InputStream inputStream) throws IOException {
try (inputStream) {
return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
}
}
我建议使用StringWriter类来解决这个问题。
StringWriter wt= new StringWriter();
IOUtils.copy(inputStream, wt, encoding);
String st= wt.toString();
使用java 9中支持的java.io.InputStream.transferTo(OutputStream)和ByteArrayOutputStream.toString(String),该字符串采用字符集名称:
public static String gobble(InputStream in, String charsetName) throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
in.transferTo(bos);
return bos.toString(charsetName);
}
总结我找到的11种主要方法(见下文)。我写了一些性能测试(见下面的结果):
将InputStream转换为字符串的方法:
使用IOUtils.toString(Apache Utils)字符串结果=IOTils.toString(inputStream,StandardCharsets.UTF_8);使用CharStreams(Guava)字符串结果=CharStreams.toString(新InputStreamReader(inputStream、字符集UTF_8));使用扫描仪(JDK)扫描仪s=新扫描仪(inputStream)。使用分隔符(“\\A”);字符串结果=s.hasNext()?s.next():“”;使用流API(Java 8)。警告:此解决方案将不同的换行符(如\r\n)转换为\n。字符串结果=新BufferedReader(新InputStreamReader(inputStream)).line().collector(Collectors.joining(“\n”));使用并行流API(Java8)。警告:此解决方案将不同的换行符(如\r\n)转换为\n。字符串结果=新BufferedReader(新InputStreamReader(inputStream)).line().allel().collector(Collectors.joining(“\n”));使用InputStreamReader和StringBuilder(JDK)int bufferSize=1024;char[]缓冲区=新字符[bufferSize];StringBuilder out=新StringBuilder();Reader in=新InputStreamReader(流,StandardCharsets.UTF_8);for(int numRead;(numRead=in.read(buffer,0,buffer.length))>0;){out.append(缓冲区,0,numRead);}return out.toString();使用StringWriter和IOUtils.copy(Apache Commons)StringWriter writer=新StringWriter();IOUtils.copy(inputStream,writer,“UTF-8”);return writer.toString();使用ByteArrayOutputStream和inputStream.read(JDK)ByteArrayOutputStream result=new ByteArrayOutputStream();byte[]缓冲区=新字节[1024];for(int length;(length=inputStream.read(缓冲区))!=-1; ) {result.write(缓冲区,0,长度);}//StandardCharsets.UTF_8.name()>JDK 7return result.toString(“UTF-8”);使用BufferedReader(JDK)。警告:此解决方案将不同的换行符(如\n\r)转换为line.separator系统属性(例如,在Windows中转换为“\r\n”)。String newLine=System.getProperty(“line.sepaper”);BufferedReader读取器=新的BufferedReader(新的InputStreamReader(inputStream));StringBuilder result=new StringBuilder();for(字符串行;(行=reader.readLine())!=null;){如果(result.length()>0){result.append(换行符);}result.append(行);}return result.toString();使用BufferedInputStream和ByteArrayOutputStream(JDK)BufferedInputStream bis=新缓冲输入流(inputStream);ByteArrayOutputStream buf=新ByteArrayOutputStream();for(int result=bis.read();结果!=-1.result=bis.read()){buf.write((字节)结果);}//StandardCharsets.UTF_8.name()>JDK 7return buf.toString(“UTF-8”);使用inputStream.read()和StringBuilder(JDK)。警告:此解决方案存在Unicode问题,例如俄语文本(仅适用于非Unicode文本)StringBuilder sb=新StringBuilder();for(int ch;(ch=inputStream.read())!=-1; ) {sb.append((char)ch);}return sb.toString();
警告:
解决方案4、5和9将不同的换行符转换为一个。解决方案11无法正确使用Unicode文本
性能测试
小字符串(长度=175)的性能测试,github中的url(模式=平均时间,系统=Linux,分数1343最好):
Benchmark Mode Cnt Score Error Units
8. ByteArrayOutputStream and read (JDK) avgt 10 1,343 ± 0,028 us/op
6. InputStreamReader and StringBuilder (JDK) avgt 10 6,980 ± 0,404 us/op
10. BufferedInputStream, ByteArrayOutputStream avgt 10 7,437 ± 0,735 us/op
11. InputStream.read() and StringBuilder (JDK) avgt 10 8,977 ± 0,328 us/op
7. StringWriter and IOUtils.copy (Apache) avgt 10 10,613 ± 0,599 us/op
1. IOUtils.toString (Apache Utils) avgt 10 10,605 ± 0,527 us/op
3. Scanner (JDK) avgt 10 12,083 ± 0,293 us/op
2. CharStreams (guava) avgt 10 12,999 ± 0,514 us/op
4. Stream Api (Java 8) avgt 10 15,811 ± 0,605 us/op
9. BufferedReader (JDK) avgt 10 16,038 ± 0,711 us/op
5. parallel Stream Api (Java 8) avgt 10 21,544 ± 0,583 us/op
对大字符串(长度=50100)、github中的url进行性能测试(模式=平均时间,系统=Linux,得分200715最好):
Benchmark Mode Cnt Score Error Units
8. ByteArrayOutputStream and read (JDK) avgt 10 200,715 ± 18,103 us/op
1. IOUtils.toString (Apache Utils) avgt 10 300,019 ± 8,751 us/op
6. InputStreamReader and StringBuilder (JDK) avgt 10 347,616 ± 130,348 us/op
7. StringWriter and IOUtils.copy (Apache) avgt 10 352,791 ± 105,337 us/op
2. CharStreams (guava) avgt 10 420,137 ± 59,877 us/op
9. BufferedReader (JDK) avgt 10 632,028 ± 17,002 us/op
5. parallel Stream Api (Java 8) avgt 10 662,999 ± 46,199 us/op
4. Stream Api (Java 8) avgt 10 701,269 ± 82,296 us/op
10. BufferedInputStream, ByteArrayOutputStream avgt 10 740,837 ± 5,613 us/op
3. Scanner (JDK) avgt 10 751,417 ± 62,026 us/op
11. InputStream.read() and StringBuilder (JDK) avgt 10 2919,350 ± 1101,942 us/op
图表(性能测试取决于Windows 7系统中的输入流长度)
性能测试(平均时间)取决于Windows 7系统中的输入流长度:
length 182 546 1092 3276 9828 29484 58968
test8 0.38 0.938 1.868 4.448 13.412 36.459 72.708
test4 2.362 3.609 5.573 12.769 40.74 81.415 159.864
test5 3.881 5.075 6.904 14.123 50.258 129.937 166.162
test9 2.237 3.493 5.422 11.977 45.98 89.336 177.39
test6 1.261 2.12 4.38 10.698 31.821 86.106 186.636
test7 1.601 2.391 3.646 8.367 38.196 110.221 211.016
test1 1.529 2.381 3.527 8.411 40.551 105.16 212.573
test3 3.035 3.934 8.606 20.858 61.571 118.744 235.428
test2 3.136 6.238 10.508 33.48 43.532 118.044 239.481
test10 1.593 4.736 7.527 20.557 59.856 162.907 323.147
test11 3.913 11.506 23.26 68.644 207.591 600.444 1211.545